The invention relates to an improved funnel with a shut-off valve. Although use of a funnel can often make it easier to fill a container with fluid and helps to prevent spills, when a funnel is placed within the opening of a container, it is often difficult or impossible for the user to view the amount of fluid in the container. Without a view of the fluid in the container, if the capacity of the container is improperly estimated, the user will often overfill the container and spillage occurs. In addition to the inconvenience caused by such spills, when certain liquids are poured the spills can be hazardous. The funnel of the present invention provides a shut-off valve which prevents spills caused by overfilling of the container.
Attempts to provide funnels with shut off valves have previously been made as shown in U.S. Pat. No. 4,712,595 (“the '595 patent”) and U.S. Pat. No. 5,458,168 (“the '168 patent”). Each of these patents provides for the use of a single permanent magnet and a magnetically attractable element to close a valve. In order to maintain the valve in a closed position, the force of the magnet must overcome the weight of the float along with downward forces acting on the float. The '168 patent teaches the use of a spring to compensate for the weight of the float in order to improve the effectiveness of the valve. In order to function properly, however, the spring force associated with the spring must be provided in a relatively narrow range. If the spring force is too great, it will be difficult to maintain the valve in an open position during the filling process. If the spring force is too small, it will not sufficiently compensate for the weight of the spring. In addition, once the float has been raised, the spring provides less lift to the float. Finally, the spring is inconveniently provided in the funnel reservoir therefore is subjected to the fluid to be provided to the container. Upon draining the fluid from the funnel fluid remains on the spring creating a difficult surface to clean.
Another problem encountered is providing a valve which is consistently activated at a predetermined fluid level within the container to be filled. Although it is desired that the valve is activated solely in response to the fluid level in the container, several other factors impact the closure of the valve. For example, the flow rate of the fluid through the funnel, the viscosity of the fluid flowing through the funnel, and the temperature of the fluid flowing through the funnel are all factors which impact closure of the valve. In order to provide a valve which consistently closes at a predetermined fluid level within the container, it is desired that the influence of these other factors be minimized.
A specific problem recognized in the '168 patent is that fluid flowing through the spout can form a liquid column which acts on the float causing premature closure of the valve. The '168 patent purports to solve this problem by constricting the flow of fluid from the upper portion of the funnel to the spout. As a result of the constriction, however, the time necessary to fill the container is undesirably increased. In addition, air holes are provided in the spout of the '168 patent to reduce the possibility of air forming a subpressure on the upper side of the float. As recognized in the '168 patent, however, these air holes create the risk of fluid flowing out of the holes to the outer surface of the funnel. Such leaking of the funnel is undesirable especially when hazardous fluids are being handled.
Yet another problem encountered, is providing a valve which allows for a fluid tight seal, eliminating leakage at the valve site.
Finally, another problem encountered is maintaining the valve in the closed position, despite inadvertent contact with the funnel.